The long range purposes of this project are (1) to improve clinical classification of selected degenerative diseases of the retina and choroid by means of detailed, longitudinal studies of retinal function and clinical laboratory tests, and (2) to provide a clinical resource for related laboratory investigations of the cause, prevention and therapy of these diseases. The degenerations of the eye such as retinitis pigmentosa are often of familial or genetic origin and must be distinguished from nonprogressive forms of night blindness and from drug or other toxicity. Degeneration of the macula also occurs in some of these diseases. Animal models are used for related investigations of retinal functions, degenerations and toxicity. Serum, biopsy and autopsy specimens available because of this project have been studied in the laboratory via project Z01 EY 00134-03 LVR (biochemical and tissue culture studies). BIBLIOGRAPHIC REFERENCES: Bergsma, D.R., Wiggert, B., Funahashi, M., Kuwabara, T., and Chader, G.: Vitamin A receptor in normal and dystrophic human retina. Nature 265: 66-67, 1977. Bergsma, D.R.: The Usher syndrome: Clinical definition and related research, In Proceedings of the Usher Syndrome Conference, Helen Keller National Center for the Deaf-Blind, Port Washington, NY, Dec. 1-3, 1976 (in press).